1. Field of the Invention
The present invention relates to an apparatus for managing consumables of an image forming apparatus which are widely used in printers, such as multi-function printers (MFP). More particularly, the present invention relates to an apparatus using a memory for managing consumables of an image forming apparatus.
2. Description of the Related Art
Generally, a facsimile machine, a printer, a copier, and an MFP which combines the functions of a printer, scanner, copier or facsimile machine include an image forming apparatus.
FIG. 1 shows a schematic block diagram of a conventional image forming apparatus and FIG. 2 shows a schematic view of an engine device of the apparatus shown in FIG. 1.
Referring to FIG. 1, the conventional image forming apparatus includes a control unit 10 controlling an overall operation of the apparatus, an interface unit 20 for connecting a computer and the apparatus to receive printing data from the computer, a storage unit 30 for storing a variety of control programs necessary for driving the apparatus and data generated by executing the control programs, an engine device 50 for carrying out a print process, an engine control unit 40 for driving the engine device 50 according to a control of the control unit 10, a high voltage power supply 80 for applying a predetermined voltage to each roller of the engine device 50 according to a control of the control unit 10, and a sensor unit 90 for detecting a printing error like a paper jam or shortage of paper. The engine device 50 shown in FIG. 2 is provided with a charge roller 51, an organic photoconduction cartridge (OPC) 52, a laser scan unit (LSU) 53, a development roller 54, a feed roller 55, a transfer roller 56 and a fusing unit 57, for printing image data on the paper.
The development roller 54 and the transfer roller 56 as shown in FIG. 2 are respectively connected with color development cartridges YC, MC, CC, BC for color prints and an image transfer belt (ITB) as shown in FIG. 3.
Printing procedures of the engine device 50 having the structure of FIG. 2 are typically as follows. The high voltage power supply unit 80 applies voltages to each roller 51, 54, 55, 56, 57 of the engine device 50 according to a control of the control unit 10. Herein, the high voltage power supply (HVPS) 80 generally applies a charge voltage of −1.4 kV to the charge roller 51, a transfer voltage of +2.0 kV to the transfer roller 56, a development voltage of 300V to the development roller 54, a feed voltage of 500V to the feed roller 55. Therefore, the charge roller 51 charged by the high voltage and engaged with the OPC 52 rotates to uniformly charge the photoconductor formed on an outer circumference of the OPC 52. Herein, the LSU 53 receives a control signal from the control unit 10, the control signal allowing an image light corresponding to an image data inputted from control unit 10 to be scanned onto the OPC 52. Accordingly, a laser diode (LD) provided in the LSU 53 is turned on and projects the image light corresponding to the received control signal to the OPC 52. As a result, an electrostatic latent image to be printed, charged by the image light of the LSU 53, is formed on the surface of the OPC 52. Meanwhile, a potential difference is generated between the feed roller 55 to which the high voltage is applied and the development roller 54 to which the voltage lower than that of the feed roller 55 is applied. Accordingly, a toner charged negatively moves to the development roller 54 from the feed roller 55 and is coated on the electrostatic latent image formed on the surface of the OPC 52 to form a toner image. The transfer roller 56 to which the high voltage from HVPS 80 is applied transfers the toner image formed on the electrostatic latent image of the OPC 52 to a paper. The toner image transferred on the paper is fused on the paper by high temperature and high pressure of the fusing unit 57, thereby ending a printing process.
As described above, a plurality of consumables such as development cartridges YC, MC, CC, BC, the ITB unit, the OPC unit and so on such as shown in FIG. 3, are needed for the image forming apparatus to print an image, particularly a color image. In FIG. 3, YC indicates the development cartridge for yellow color, MC indicates the development cartridge for magenta color, CC indicates the development cartridge for cyan color, and BC indicates the development cartridge for black color.
As shown in FIG. 3, key resistances Ry, Rm, Rc, Rb, Ri, Ro provided in the conventional consumables allow the control unit 10 of the image forming apparatus to detect the amounts of colors in the consumables for refilling or replacing the consumables.
The key resistances provided in the respective consumables are respectively connected to pull-up resistances R1 provided in a main board 1 of the image forming apparatus as shown in the FIG. 3, and are also connected to respective ports of the control unit 10. The other terminals of the respective key resistances are grounded, and the other terminals of the respective pull-up resistances are supplied with a power supply voltage Vcc. As shown in FIG. 4, the key resistances vary according to the time of use or consumption of contents (such as ink or toner) of the consumables. The voltage applied to control unit 10 also varies according to the variation of the key resistances. The control unit 10 functions to perceive the consumables, and/or to prevent refill of consumables, and/or to detect the consumables' life span, and so on, through the variation of key resistance.
The conventional apparatus for managing consumables of an image forming apparatus with key resistances provided in the consumables has several disadvantages.
First, the control unit of the image forming apparatus needs as many key resistance sensing ports as the number of consumables to individually detect the key resistances provided in the consumables. For example, as shown in FIG. 3, the control unit 10 of the image forming apparatus needs at least six ports for detecting the individual key resistances of four development cartridges, the ITB, and the OPC. That is, the control unit of the conventional image forming apparatus needs more ports for detecting the key resistance as the number of consumables increases.
Second, a control program of the control unit 10 to individually control the respective ports corresponding to the key resistance of the consumables is very complicated.
Third, signal connection lines and an electrical wire harness to respectively connect the key resistances of the consumables to the ports of the control unit have a complicated structure. Therefore the price of the apparatus increases.
Fourth, it is hard to substantially detect the refill of contents (such as ink or toner of the development cartridge) of the consumables with the key resistances. Therefore, the refill of contents is not practically prevented.
Fifth, if there are many OEM venders manufacturing the consumables, it is hard to identify the OEM venders.